Photographic elements having a light-sensitive silver halide layer and a stripping layer composed of a polyvinyl pyridine quaternary salt and process of using such elements



Sept. 30, 1952 l J. Q. UM ERGER 2,612,446 PHOTOGRAPHIC ELEMENTS HAVIN A LIGHT-SENSITIVE SILVER I HALIDE LAYER AND A STRIPPING LAYER COMPOSED OF A POLYVINYL PYRIDINE QUATERNARY SALT AND PROCESS OF usmc SUCH ELEMENTS Filed Sept. 15, 1949 GELATIN ANTl-ABRASION LAYER GELATIN SILVER HALIDE,

POLYVINYL PYRIDINE ETHIODIDE GELATIN SILVER HALIDE COLLOIDAL SILVER GELATIN SUBLAYER CELLULOSE NITRATE FILM BASE W INVEN TOR.

JA COB QUENTIN UMB ERGE R BY A T TORNE Y.

Patented Sept. 30, 1952 PHOTOGRAPHIC ELEMENTS HAVING A LIGHT-SENSITIVE LAYER AND A STRIPPING LAYER COM- POSED OF A POLYVINYL PYRIDINE QUATERNARY SALT AND PROCESS OF USING SUCH ELEMENTS Jacob Quentin Umberger, Holmdel, N. J assignor to E. I. du Pont de Nemours and Company, Wilmington, DeL, a corporation of Delaware Application September 15, 1949, Serial No. 115,943

This invention relates to photography and more particularly to photographic elements including films, plates and papers which bear at least one light-sensitive silver halide layer which is adhesively joined to the support or to another colloid silver halide emulsion layer on a support by means of a stripping layer composed of a polyvinyl pyridine quaternary salt. The invention also relates to a process for transferring an image-bearing layer or layers from the above stripping elements to another support.

An object of this invention is to provide a new photographic stripping element. A further object is to provide photographic stripping films. Another object is to provide multilayer photograpic films which can be individually separated from each other at difierent stages during processing. A further object is to produce such elements whereby the stripping action can be controlled by the use of aqueous treating baths. Another object of the invention is to provide a method for insolubilizing a polyvinyl pyridine quaternary salt stripping layer and resolubilizing it so stripping can be accomplished. A still further object is to provide a simple, economic method for delaying the stripping action of a film having a polyvinyl pyridine quaternary salt stripping layer. Still other objects will be apparent from the following description of the invention.

It has been found that photographic stripping elements can be prepared by using as the stripping layer or stratum a water-soluble polyvinyl pyridine quaternary salt. These salts adhere to a film base such as a cellulose deriv'ative, e. g., cellulose acetate or cellulose nitrate, cellulose acetate propionate, cellulose acetate butyrate, superpolymers, e. g., nylon and polyesters, e. g., ethylene glycol-terephthalic acid polymers; metal foils, papers, e. g., baryta coated paper or to such supports which have a thin anchoring substratum composedof a'water-permeable colloid e. g., gelatin. A light-sensitive water-permeable colloid silver halide emulsion layer can then be coated onto the polyvinyl pyridine quaternary salt layer and has good adherence to it. The light-sensitive silver halide layers, however, can be readily removed from the support or supporting layer by treating the element in an aqueous bath and then stripping off the latter.

The adherence of the stripping layer to the support and light-sensitive layer or water-permeable membrane bearing a colloid silver halide emulsion layer can be modified in various manners whereby one can obtain control over the stripping action. i

21 Claims. (01. 95-2) SILVER I-IALIDE It has been found that polyvinyl pyridine quaternary salt stripping layers can be insolubilized and thereby converted to non-stripping layers or rendered quite diflicult to strip by treating them with an aqueous solution containing a water-soluble anionic wetting agent. Suitable agents of this type include the sodium, potassium and ammonium salts of decyl, dodecyl, tetradecyl, hexadecyl, octadecyl and oleyl sulfate and the triethanolamine, triethylamine, cyclohexylamine, pyridine and tetraethyl ammonium salts of such sulfates. The insolubilized layers can be resolubilized by treatment with an aqueous solution containing water-soluble cationic surfaceactive wetting agent containing an aliphatic hydrocarbon radical of 8 to 20 carbon atoms, e. g., dodecyl, pyridinium chloride, cetyl pyridinium chloride, octyl-, decyl-, dodecyl-, and octadecyldimethylbenzylammonium chloride and cetyldimethylbenzylammonium chloride. The insolubilizing treatment can be effected prior to formation of the layer but in the preferred form of the invention is effected after the photographic stripping element is made and exposed and before or after development or fixation but prior to any extended washing in water.

The anionic surface-active wetting agents apparently enter into a metathetical or double decomposition reaction with the polyvinyl pyridine quaternary salt whereby the anion of the latter salt is replaced by the anion of the anionic surface-active wetting agent and the resulting polyvinyl pyridine quaternary salt is markedly less water-soluble than that of the original polyvinyl pyridine salt. The resolubilizing action takes place along similar lines and a water-soluble polyvinyl pyridine quaternary salt is later regenerated.

Various water-soluble polyvinyl pyridine quaternary salts can be used as stripping layers of the above photographic elements. Among the useful salts are the poly-N-all ylvinylpyridinium chlorides, bromides and iodides, polyvinyl pyridinium methyl-p-toluene sulfonates, polyvinyl pyridinium metho-methylsuliates and the polyvinyl pyridine etho-ethylsulfates. I a

The preparation of the poly-N-alkylvinylpyridinium chlorides, bromides and iodides can be accomplished by reacting an alkyl bromide, chloride or iodide with a solution of a polyvinyl pyridine, e. g., by reacting ethy1 bromide with the polymeric vinylpyridine dissolved in an inert solvent such as alcohol. Detailed methods for preparing such compounds are described in Richards U. S. Patent No.2,48'7,829. p

The polyvinyl pyridinium metho and etho The preparation of various polyvinyl pyridines in Australian application useful for making the quaternary salts used in accordance with this invention as stripping layers is described in Schulze U. S. Patent 2,448,552.

"The polyvinyl pyridine quaternary salts from 2- vinylpyridine and 4-vinylpyridine polymers are preferred.

The vinylpyridine polymer quaternary salt lay- Asample 'of rioly-Z-vinylpyridine prepared as ers which have been insolubilized by the foregoing treatment can be modified so that they again become'quite water sensitive or water-soluble by treating the film element containing the insolubilized vinylpyridine. polymer quaternary salt layer in an aqueous solution containing a cationic surface active wetting agent. The layer so modifiedcan then be readily stripped from the remaining strata and support. 7

.The stripping procedure can be combined with a transfer operation to a gelatin blank or other typeof blank film. Hence an'important aspect ofthe invention is concerned with a combination of the steps of ins'olubilizing the vinylpyridine polymerquaternary salt layer, resolubilizing such layer and stripping the light-sensitive silver halide emulsion layer carried by the stripping layer from the suppprt or remaining layers carried by the support. The stripping operation as previously mentioned can be combined with a transfer operation whereby the image-bearing layer can be transferred to a new support.

The above procedures are applied to the film elements after, they have been exposed and containlimages -(latent images) and can be carried out either before o'r'after development. When the 4 fied in accordance with the desired stripping sequence. v

Thisisso because the-cationic surface active wetting agents which solubilize the polyvinylpyridine quaternary salt layers,,for example, have an insolubilizing action on the water soluble macromolecular acetal stripping layers. The procedures willbe further explained below.

The prepar ation of. certain polyvinylpyridine quaternary salts will now be described.

described mu. S. P. 2,448,552 was mechanically pulverized to a fine powder. Then 210 grams (2.0 moles) of the powder was placed in a suitable vessel with 1024 grams (6.57 moles) of ethyl iodide. The mixture was stirred until the powder had almost entirely dissolved; and it was then refiuxe'd'for four days on the steam bath The resulting yellow solid was pulverized and washed extensively with ether-and dried in a vacuum desiccator. A yield of 392 grams was obtained. 7

Analysis; calculatedfor 100% quaternization: I, 48.7; found: I, 38.15, 38.23 indicating the degree 'of qu'aternization was approximately 59.4%

PROCEDURE 1i Poly4-vinylpyridine ethiod-ide V A 10.5 gram (0.10 molelsample of powdered poly-4-vin'ylpyridine (prepared in a manner similar to that described in U. S. P. .'2,448,552) was dissolved in'500 milliliters of absolute methanol. (The'poly-4 vinylpyridine employed was of moderatelyhigh molecular weight, having a viscosity filmelement contains two or three light-sensi:

tive silver halide layers they may be developed before the stripping operation is carried out. In this wayiall latent images aredeveloped in one bath. When the stripping and transfer operation -isconducted prior to development the separate layers can-thenbe individually developed.

A further aspect of the invention is concerned withnovelstripping films which have three lightsensitive silver halide layers and two different types of stripping layers between different lightsensitive colloid silver halide emulsion layers, one of the stripping layers being composed of a quaternary salt of a vinylpyridine polymer and the other a water-soluble macromolecular acetal of a hydroxyl polymer having a plurality of recurring intralinear jacent to light-sensitive .silver halide layers which are to be removed.

In the multilayer films just described the stripping layers may be in either order. vThe processing baths however will have .to-be modifor a 1% methanol solution of 3.8 centipoises.) To the methanol solution was added 7.8 grams (0.05 mole). of ethyl iodide. The mixture was then refluxed for four days without separation of a solidi The solution was then diluted with ether until a volume of two liters was reached; at this point the 'poly-4-vinylpyri'dine ethiodide sepa-' rated as a p'ale'yellow solid. The'solid was filtered off, washedwithfdry ether and dried'ina vacuum desiccator. Themateri'al was originally hygroscopic, but onceit had been completely dried,'it appeared to be unaffected by atmospheric moisture. The'yield'amounted to '16 grams ofa'lemon yellow solid .(88 %1of theory, based on 50% conversion to the'quaternary salt).

Analysis: Calculated for 50% quaternizati'on:

, I, 34.7; found: .I,31.9 4'and 31.61indicating the degree of quaternization was approximately 43.2%. g I

PROCEDURE. III

7 PoZy-4-vinylpyridine 'e th'z'odide;

A 10.5 gram (0;10 mole) sample'of powdered poly-4-vinylpyridine (prepared. in 'amanner similar to that described in UVS. ;P. 2,448,552) was dissolved in 500 milliliters of absolutemethanol. To the solution was added 62.4 grams (0.40 mole) of ethyl iodide. (This represents a-.300% eX- cess.) The mixturewas heated on the steam bath for four days; at the end of thistime the ethiodide quaternary salt had separated as a yellow gummy solid. The alcohol was-decanted and the materialmechanically removedfrom the flask bymeans of a stainless steel rod. The tacky solid thus obtained was suspended in "ether, the ether was decanted and the solid was'pulverized and rewashed with ether. After drying in a vacuum desiccator there was obtained 24.5,

EXAMPLE 1 A cellulose nitrate film base I as shown in Fig.

1 of the drawing having a thin gelatin substratum 2 was coated with a gelatin silver iodobromide emulsion which had admixed therewith 50% (by weight based on the silver salt) of yellow colloidal silver prepared as described in U. S. P 2,462,503,

to a weight of 52 mg. silver halide per square decimeter and the resulting layer 3 was dried.

Ten grams of polyvinyl pyridine ethiodide prepared in accordance with Procedure I above and processing of film ele- I Per cent Gelatin 4.60 Chrome alum aqueous solution (10%)---- 0.80 Saponin 1 -1 0.02

- Water 94.58

and having one-half of the tertiary amino groups quaternized was added to 300 ccs. of distilled water, 2.5 grams of low viscosity polyvinyl alcohol (99% hydrolyzed polyvinyl acetate), 13.3 cos. of 5% saponin solution and additional distilled water was added until a total of 633 grams of water were present. There was then addedsufficient 1N NaOI-I'to raise the pH to 70:01. The I resulting solution was coated onto the silver halide emulsion layer 3 to a weight of 20-30 mg.

of dry polyvinyl pyridine ethiodide per square decimeter and the layer 4 dried.

A gelatino-silver iodobromide emulsion containing 1,l-diethyl-2,2-cyanine iodide as an ortho-sensitizing dye was coated on the polyvinyl pyridine ethiodide layer to a weight of approximately 48 milligrams silver halide per square a standard negative sensitometer, developed for i a period of 15 minutes in an aqueous solution made by admixing the following components:

Water (125 EL cc 150.0 N -methyl-p-aminophenol sulfate grams 0.8 Sodium sulfite (desiccated) do 90.0 Hydroquinone do 1.0 Borax do 3.0 Cold water to make 1.0 liter.

fixed without rinsing for a period of 15 minutes in a solution made by admixing the following ingredients:

Water (120 F.) cc 850.0 Sodium thiosulfate grams 300.0 Sodium sulfite (desiccated) do 11.0 Acetic acid (glacial) do 17.0 Potassium alum do 10.0

Cold water to make 1.0 liter.

washed in water at 60 F. for a period of 10 min utes and immediately dried, soaked for 90 seconds in. a bath A (containing grams of sodium dodecyl sulfate dissolved in 1000 cos. of distilled water and adjusted to pH2 with HCl) maintained at a temperature of 7 0 to 72 F. The outer gelatin layer was then rolled in contact with a gelatin coated blank film (made by coating a cellulose nitrate film base to a weight of 70 mg. of dry the solution being adjusted to pH 4.7 with sulfuric acid before coating). a

The two gelatin layers of the multilayer film and blank film were left in contact for a period of 60 seconds and then separated. The silver halide emulsion layer readily separated and had strong adherence to the blank film. The sodium dodecyl sulfate promoted anchorage between the gelatin surface of the blank film and the gelatin surface of the stripping film'. There was no noticeable insolubilization of the polyvinyl pyridine stripping layer because of a lack of penetration through the outer gelatin layer of the film.

EXAMPLE 2 A film element similar to that described in Example 1 was prepared except that in place of the polyvinyl pyridine ethiodide, which was 50% quaternized, there was substituted an equivalent amount of a completely quaternized polyvinyl pyridine ethiodide, exposed, developed, fixed,

washed and dried and then processed as described in that example. Similar results were obtained. EXAMPLE 3.

EXAMPLE 4 A film element-identical to that described in 1 Example 2 was prepared, exposed, developed,

fixed, washed and dried and then processed as described in that example except it was soaked for aperiodof 12 minutes in the sodium dodecyl sulfate bathe It was found that this soaking period insolubilized the polyvinyl pyridine ethicdide layer and prevented a successful stripping operation. i

EXAMPLE 5 A film element identical with that described in Example '1 above and processed in a similar manner except that 25 grams of sodium tetralin sulphonate were substituted for the sodium dodecyl sulfate in the example. Due to the greater migrating power of sodium tetralin sulfate, the polyvinyl pyridine ethiodide layer became highly insolubilized and a successful stripping action could not be obtained.

Similar results were obtained by using the film element described in Example 2.

EXAMPLE 6 A film element of the type described in Examplel was prepared, exposed, developed, fixed, washed and dried as described in Example 1. The film was then soaked for a period of 10 minutesgin bathjA; (see Example 1). This iihn was layer and the gelatinblank cuti into;strips td ll and: which: were treated.

as follows:

(mas-naked for minutes in distilled water ad 'jiustedto .pHLZwithl-ICL c (bl). Soaked-l for lofiminutesc 'inl 2.5%. a que aous 'dodecyltrimethyl. ammonium bromide adjusts: ;:edto.pI-12.with.HCl..

The; polyvinyl nyridine 'layer in strip- (a). was uic'cessful strippi action was; obtained: Strip-.g(,b howeven. was, solubilized. Itwas; soakedling bath A for: a; period; of; 30:v seconds and; then rolledyim contact. with a;

made quite insoluble and;

gelatin blankg. film-K as; described in; Example: 1'.

The; outer gelatino: silver; halidaemu'lsion layerreadily' stripped; from the. remaining: emulsion.

layer. of: the; original front him; and: was transferred to thegelatin: blanlefilm and, had. excellent: adherencethereta Similarresultszwere;obtained.

by substituting theifilm: o:Example:2.:

" EXAMPLE '1 I 1 A multilayer film of the type described in Exthen soakedior ten minutes in bath A and the,

polyvinyl pyridine ethiodide layer" was made" highly insoluble. The insol'ubilized filmelement was-cut into; strips (A): and (-B) which were treated a followsz I tion of 25 grams di-o-tolyl guanidine base in one liter of distilled H2O adjusted to pH 2 with H01. The insolubilized strip layerwas quickly resolubilized. 'Emulsionjltransfer' was. accomplished by' soaking" the, resclubili'zed filmuin an rc horing bath A for 30', seconds, rolling; incontact. with, blank film? and transferring (B); Soaked. rorr twq minutesjin.distilledHaQadr :iustem pH? with HQ1T- Norresolilbilizing oer.

curredj evenj when the, soaking time wasrexe.

tendedtto 30minutes. I I Similar results'were obtained by processing the film of Example Z-in l-ihe manner.

s layer 12: of: .polyez-vinylpyridinium; metho-ptoluene sulfonate was coatedontathaortho silver halide.v emulsion layer H; from a. solution con- I fisfllrsramsnmonosodimm:dihydrogen: phosphate 'ample 1 was exposed, developed, fixed, washed I and dried-as described in that example. Itwas taining Bi-grams ;of the quaternary :salt: in 100. cc:

of water toathicknessnofi 3 microns;

' A gelatino silver iodobromide emulsion which:

had admixed therewith'r50l% f -(by weight based. on the silver. halide )J, of yellow, colloidal sillven pres pared= as described" in -Uz' S; P. 2,4:62,503.;..was; coated onto the polyvinyl pyridine salt layer I2 to form layer l3 havih'a'weight of 50 milligrams of silver halide persquare decimeter.

Difierential s'tripping of the film= elementjust described is obtained follows:

(--1,)--. Soak e 12 minutesgin'lsolutionc.

o as-me: ziizmgrams-sodium'dodecyl sulfate, 1 25,0 grams sodiumrtetralin sulfonate;v

116.05 gramsrcitric jaci'd', ;,and5;

":imonohydrateri: r t, "Distilled H2O added to makes'Lo-liten.

- 4sfcc.i8,5% vphosphoriciacict to. make: pI-Ii22 T (2*)? Roll in. c-ontact'gwithlgelatin;blank. film;,

I I (iii/soaked for tworminutesrin arr aqueousesolu- (3 Strip.-apartiwith:resultanttransfer'of outer" two; emulsion layers: to the: gelatin blank .film;

(4 );:KVash gelatin rblanktfilm carrying two outer. emulsion-layers Ito'reniove insolubilizingE-scdium tetralin sulfonate from: cationic; strip; layer; (about '6 min'utesv' required);

(5*) Roll' in: oonta'ct wlith: gelatin blankifilm either Y A icell'ulose acetate fi l'ni bfa se' 'l asshown irrFig;

2 of the drawing having" athing gelatin; anchoringsubstratumyd was coated with a green blin'd;

tred sensitive-gelatinsilveriodobromideemulsion, I containing 'the dye of Example IV of U; S.,P atent milligrams silver halide per-square decimete'r and the resulting layer 9 was dried. After drying; a solution containingzfi'ogramspf a polyvinyl ace- I tal per 1000 grams of ethanoL obtained by heat! ing -the mixture 45 minutes at l25"'F. and cooling to 90 was coated on the emulsion layer, to.

form a layer l0 whichihadiathickness off020001;

inch; This acetal'was prepared'by stirring aimixr' ture of 44 parts of 100% hydrolyzed polyvinyl acetate: (medium; viscosity. j molecular, weight 1'5,000t0;20,000')', 40' parts of glaQihliacetaic-acid;

40 parts of sodium-o benzaldehydesulphonate=- c monohydrate and 6 parts of 85 fphosphoricwacid at 75 C. to 80 C; for one totwo hours The product is then precipitated by the addition of 1000 parts each of acetone and dried to give 75 parts of the polyvinyl acetal in the form of a white solid;- A: gelatino silver'iodobromide emulsion: layerw. Il containing 1 ,1"-diethyl-2,'2' -cya-- nineciodide as an orthor-sensitizing dye was-coated on. the,- polyvinyl acetal layer llllto', a weight of'60'.

milligrams? silver halideperssquare decimeter; A

directly or immediatelyi'after"30 secondsdn an-- h g batl'i'A lse t ga p I I I I I Fapart with 'resultano' transf Ofi ml s n ayern ers in thenphotographicfilin, of this example-can be changed. inl' order if-fjdesired' with similarre? 1 sults.l 3 v A- film elemento f the kind described in' Ex ample 8 was soakedfor one minute in aresolubilizing bath made by dissolving 25 grams'of diq-otolyl guanidine' in onef liter of water" and adding concentratedjhydrochloricacid'to a pH 2 (solo-'- tionD'y instead of washing for'six'minutes' in"- water as; described in stepv (4) ofqthati example with analogousresults except that: the.resolu-;-

bilizing actionwas, more, rapid;

.7 P IW. A film element like that of 'Exa m'ple'9 exeept in place of the yellow colloidalsilver used in the filter' layer there was substituted the yellow" filterdye'des'eribed in U; S. Patent'2g274ifl82: The

yellow filter dye was found to be stronglyconcentratedi in the layer of polyvinyl pyridine quaternary salt apparently because it was. a-

strongly charged acid dye; Thafilm'element-was exposed, developed, fixed, washed and: dried. as. inExample 1 and then processed asrfollowsi (1) Soaked in wateriorrsolution C.(Example;8), for 3 minutes.

('2 Rolled. into contact with: the gelatin: surface-cf.;,a gelatin "blankzfilm" (39. Stripped "apart; thus; transferring: the :twotv outenimage .bearing.:silverthalide: emulsion layers tozthessuppflrti ior the gelatirr blank;

(4): Thezgelatin .blank-zfilm with the two" adhe'rent: images," bearing:- layers and interrelated" vinylpyridineepolymer salt layer: is then soaked im'a solutionzD (Example 9 for2 minutes'thus Th position lief. thelereenlandred sensitive layresolubilizing the vinylpyridine polymer salt layer.

(5) Soakedin bath A. (Example 1) for 90 seconds.

(6) Rolled in contact with a gelatin blank film.

(7) Stripped with the resultant transfer of one imagebearing layer to the new support.

The stripping film described in Example 9 and similar films need not have the polyvinyl acetal stripping layer wholly composed of such acetals. However, these polymers should constitute the essential and predominant part of the stripping layers. There may be mixed with one or more of such acetals water soluble or hydrophilic hydroxyl polymers, e. g., polyvinyl alcohol of low, medium or high viscosity, or partially hydrolyzed vinyl esters, polyvinyl acetate and polyvinyl chloracetate, polyvinyl acetals of formaldehyde, acetaldehyde, benzaldehyde, etc., wherein there is sufficient free hydroxyl groups to confer watersoluble or hydrophilic properties. This also is true of the polymeric quaternary salt strip layers, for example, low viscosity, completely hydrolyzed polyvinyl alcohol may be mixed in suitable proportions.

Also, in place of the specific polymeric acetals of the vinyl alcohol of the above examples, there may be substituted similar acetals of other aldehydes containing carboxylic and/or sulfonic acid roups. Suitable additional aldehydes include aliphatic sulfoaldehydes of the formula HSOACHQMCHO, where n is 2 to 10, e. g., betasulfopropionaldehyde, aliphatic carboxyaldehydes of the formula HOOC(CH2)71.CHO, where n is 2 to 10, e. g, beta-formylpropionic acid; benzaldehyde-parasulfonic acid, terephthalaldehydic acid, p-(beta-formylethyl) -benzoic acid and o-carboxymethoxybenzaldehyde.

Films containing two or more stripping layers composed of the same or different polyvinyl pyridine salts of the above type can be made in accordance with the invention.

In place of the gelatin used for the binding agent for the silver halide grains, there may be substituted other hydrop-hilic colloids, e. g., agar agar, polyglycuronic acids, zein, collodion, watersoluble cellulose derivatives such as substantially hydrolyzed cellulose acetate, cellulose esters of hydroxy monocarboxylic acids, e. g., lactic or glycolic acids, alkali metal salts of cellulose esters of dicarboxylic acids such as phthalic acid, polywater-soluble polyvinyl acetals and other hydrophilic synthetic or natural resins and polymeric compounds. Suitable hydrophilic colloids of the above type are described in United States Patents 2,110,491, 2,276,322, 2,276,323, 2,286,215, and 2,211,323.

The present invention has the advantage that it provides a novel and practical method of temporarily insolubilizing a water-soluble stripping layer. This temporary insolubilization is of importance in commercial photographic processing laboratories in that it permits one to carry out the stripping operation in a different room from that in which the chemical photographic processing, e. g., developing and fixing, is carried out.

This means that the equipment used in the stripping operation will be free from the corrosive and toxic conditions which are present in developing rooms.

A principal advantage of the insolubilization treatment is that differential separation of a the development operation. Moreover, thestripping operation can be carried out under wellilluminated conditions thus permitting theoperator to carefully follow the stripping of each frame.

An additional advantage in the inventionis that complete processing of the front film can be accomplished while retaining adherencebetween the image-bearing records. A master positive print of the two superposed records can be made before removing the outer record. ,Hence. this record can be reformed from the master positive print in the event of damage or loss of r the outer layer during transferring it to another base, and stripping. A further advantage is that the stripping operations can be carried out at a central laboratory while production companies on location can process and view each days exposures and edit them before stripping.

As many widely different embodiments of this invention can be made without departing from the spirit and scope thereof, it is to be understood that the invention is not to be limited except as defined by the claims.

What is claimed is;

l. A photographic stripping film comprising a hydrophobic flexible support, a hydrophilic colloid silver halide emulsion layer on the. support, a layer composed essentially of wateresoluble quaternary salt of a vinylpyridine polymer on said emulsion layer and a light-sensitive colloid silver halide emulsion layer on said polymer layer. 3

2. A photographic stripping film comprising a hydrophobic flexible support, a hydrophilic colloid silver halide emulsion layer on the support, a water-soluble polyvinylpyridine quaternary salt layer on said emulsion layer and a lightesensh tive colloid silver halide emulsion layer on said salt layer.

A photographic stripping filrn comprising a hydrophobic flexible support, ahydrophilic colloid silver halide emulsion layer; on the support, a Water-soluble pQIy-Z-Winylpyridine quaternary salt layer on said emulsion layer and a lightsensitive colloid silver halide emulsion layer on said salt layer. U 1 i i q 4. A photographic stripping film comprising a hydrophobic flexible support, a hydrophilic colloid silver halide emulsion layer on the support,

a Water-soluble polyvinylpyridine ethiodide. layer on said emulsion layer and a light-sensitive c01- loid silver halide emulsion layer on said salt layer.

5. A photographic stripping film comprising a hydrophobic flexible support, a hydrophilic colloid silver halide emulsion layer on the support, a water-soluble polyvinylpyridine alko alkylsulfate wherein the alkyl group contains from 1 to 2 carbon atoms on said emulsion layer and a light-sensitive colloid silver halide emulsion layer on said salt layer.

(LA photographic stripping film comprising-a hydrophobic flexible support, a hydrophilic colloid. silver halide emulsicnlayer on the support,

a water-soluble pol'yvinylpyridine. alkyl-p-toluene I onsaid salt layer;

7-. La -photographic element comprising a transparentfi'exible; film base bearing in order on one surface a light-sensitive hydrophilic colloid silver halide emulsion layerwhich is predominantly sensitive to bluefl ight, af layer composed essentiallyiof a water 'eoluble quaternary salt of a vinylpyridine polymer on said emulsion layer and a light-sensitive hydrophilic colloid silver halide layer on'saidpolymer layer, said elementlcontaining a stratum of a yellow filtering material having good blue light absorption characteristics. 1

8; A photographic element comprising a transparent 'fiexible film'base bearing in order on one surface a'light-sensi'tive hydrophilic colloid silver halide emulsion layer which is predominantly sensitive to blue light, a layer composed essentially of a Water-soluble quaternary salt of a poly-vinylpyridine; on said emulsion layer and a lightgsensitivir hydrophilic colloid silver halide layer on said polymer layer, said element containlng a stratum of a yellow filtering material having good blue-light absorption characteristics.

9 photographic stripping film comprising a hydrophobic flexible support bearing in order a 'hydrophilic' colloid 'silverhalide emulsion layer,

a water-soluble polyvinylpyridinfi quaternary salt layer; aflight-sensitive colloid silver halide emulsion layer, a water-soluble" polyvinylpyridine quaternary salt layer and a light-sensitive colloid silver halide emulsion layer.

1'0 A photographic element comprising a hy- 'dropho'bi'c'flexible film base bearing in order on groups as polymer-forming units with an aldehyde containing a solublizinggroup taken from the; class-COOZ and SO3Z, where Z is a member taken from the group of hydrogenand a water-soluble salt-forming cation, which aldehyde is otherwise unsubstituted, and the other polymeric material is awater-soluble quaternary salt ofa vinylpyridine.polymer.

11. A photographic element as set forth in claim 19, wherein said acetal is the sodium o-sulfobenzaldehy'de' acetal of polyvinyl alcohol and said quaternary salt is a poly-Z-vinylpyridine quaternary salt, e

12. A photographic element comprising a hydrophobic film base'bearing in order on one surface a light-sensitive" silver halide emulsion layer,

' a stripping layer consisting essentiallyof a Watergroups as polymer forming units with an aldehyde containing a solubilizing group taken from the class consisting of -COOZ and SO3Z, where Z is amember taken from the group consisting of hydrogenanda Water-soluble salt-forming cation, which aldehyde is otherwise unsubstituted, a hydrophilic colloid silver halide emulsion layer, a stripping layer composed essentially of a water-soluble quaternary salt of a'vinylpyridine polymer and a light-sensitive colloid silver halide emulsion layer, said emulsion layers being differentially sensitized so that they collectively absorb" light throughout the visible spectrum.

1 32A"photographicflelement comprising a hydrophobic transparentfilm basebearing in order on one surface a gelatin anchoring substratum, a light-sensitive silver halide emulsion layer which has no sensitivity in the green region of the spectrum but has an extra range of sensitivity in the red region of the spectrum, a stripping layer consisting essentially of a water-solub1emacromolecular acetal of a hydroxyl polymer having a" plurality of recurring intralinear -cni 'JHon A groups as polymer forming units with an aldehyde containing a sol'ubilizingv group taken from v the class consisting of ,COOZ' and SO3Z, where Z is. a member taken from the group consisting of hydrogen and a water-soluble saltforming cation, which aldehyde. is otherwise unsubstituted, a hydrophilic colloid silver halide emulsion layer which has' an extra range of sensitivity in the. green region of the spectrum, a layer composed essentiallyof a Water-soluble polyvinylpyridine quaternary salt and a colloid silver halide emulsion layer containing a yellow filtering material which absorbs blue light, said layer being, sensitive in blue region of the spectrum only. v

14'. The process Whichcomprises exposing to a light, image photographicielement as described in claim,13', treating, theex-posed element in an aqueous solution containing a mixture of sodium dodecyl sulfateand sodium tetralin sulfonate, pressing the outermost layer of said element into contact with. the gelatinlayerof a gelatin blank maining', emulsion layer whereby the three image bearingv layers of the original element are disposed on separate supports.

15'. Aprocess as set forth in claim 14 wherein the washing bath contains di-o-tolyl guanidine hydrochloride.

16. A process treating an exposed photographic element comprising a hydrophobic transparent film base bearing in order on one surface a gelatin anchoring substratum, a light-sensitive silver halide emulsion l'a-yer which has no sensitivity in the green region of th'e'spectrum but has an extra range of sensitivity in the red region of the spectrum; a stripping layer consisting essentially of awater-soluble macromolecular acetal of a hydroxyl polymer having a plurality of recurring intralinear' Y f I -CH2CHOH groups as polymer forming units with an aldehyde containing a solubilizing group taken from the class consisting of -COOZ and SO3Z, where Z is a member taken from the group consisting of hydrogen and a water-soluble saltforming cation, which aldehyde is otherwise unsubstituted, a hydrophilic colloid silver halide emulsion layer which has an extra range of sensitivity in the green region of the spectrum, a layer composed essentially of a water-soluble polyvinylpyridine quaternary salt and a colloid silver halide emulsion layer containing a yellow filtering material which absorbs blue light, said layer being sensitive in blue region of the spectrum only, in an aqueous solution containing a mixture of sodium dodecyl sulfate and sodium tetralin sulfonate, pressing the outermost layer into contact with the gelatin layer of a gelatin blank film stripping the two image-bearing emulsion layers from the photographic element, washing the gelatin blank film carrying the two image-bearing layers in water, treating the two imagebearing emulsion layers in an aqueous bath containing an alkali metal salt of an alkyl sulfate containing 8 to 22 carbon atoms, pressing the outer image-bearing emulsion layer into contact with the gelatin layer of a second blank film and stripping said emulsion layer from the remaining emulsion layer whereby the three imagebearing layers of the original support are disposed on separate supports whereby the gelatin blank film with the two adherent imagebearing emulsion layers is treated in an aqueous bath containing an alkali metal salt of an alkyl sulfate containing 8 to 22 carbon atoms before the last stripping operation.

1'7. A process for decreasing the Water-solubility of a stripping layer of a photographic element, said stripping layer supporting a hydrophilic colloid silver halide emulsion layer and consisting essentially of a water-soluble quaternary salt of a vinylpyridine polymer, which comprises treating said salt with an aqueous solution containing an anionic wetting agent wherein the hydrophobic group is an aliphatic hydrocarbon radical of 10 to 18 carbon atoms.

18. A process for decreasing the water-solubility of a stripping layer of a photographic elephilic colloid silver halide emulsion layer and consisting essentially of a water-soluble quaternary salt of a vinylpyridine polymer, which comprises treating said element with an aqueous solution containing a sodium alkyl sulfate of 10 to 18 carbon atoms.

19. A process for decreasing the water-solubility of a stripping layer of an exposed photographic element, said stripping layer supporting a hydrophilic colloid silver halide emulsion layer and consisting essentially of a Water-soluble quaternary salt of a vinylpyridine polymer, which comprises treating said element with an aqueous solution containing a sodium alkyl sulfate of 10 to 18 carbon atoms 20. A photographic stripping and transfer process which comprises treating an exposed photographic film element comprising a film base having super-imposed thereon two latent imagebearing gelatino silver halide emulsion layers which are separated by a stripping layer consisting essentially of water-insoluble quaternary salt of a vinylpyridine polymer with an anionic surface active wetting agent wherein the hydrophobic group is an aliphatic hydrocarbon radical of 10 to 18 carbon atoms which comprises treating said element in an aqueous bath containing a cationic surface-active wetting agent wherein the hydrophobic group is an aliphatic hydrocarbon radical of 8 to 20 carbon atoms, pressing the outer image-bearing layer of said element into contact with the gelatin layer of a blank film comprising a transparent-film support and a gelatin layer, and stripping the image-bearing layer adhering to said gelatin layer from the remainder of the exposed photographic film.

21. A photographic stripping and transfer process which comprises treating an exposed photographic film element comprising a film base having super-imposed thereon two latent imagebearing gelatino silver halide emulsion layers which are separated by a stripping layer consisting essentially of Water-insoluble quaternary salt of a vinylpyridine polymer with an anionic surface active wetting agent wherein the hydrophobic group is an aliphatic hydrocarbon radical of 10 to 18 carbon atoms which comprises treating said element in an aqueous bath containing a cationic surface-active wetting agent wherein the hydrophobic group is an aliphatic hydrocarbon radical of 8 to 20 carbon atoms, treating the resulting element for a short period in an aqueous anchoring bath containing an anionic wetting agent wherein the hydrophobic group is an aliphatic hydrocarbon radical of 10 to 18 carbon atoms and having a pH of 1 to 4.5, pressing the outer image-bearing layer of said element into contact with the gelatin layer of a blank film comprising a transparent-film support and a gelatin layer, and stripping the image-bearing layer adhering to said gelatin layer from the remainder of the exposed photographic film.

JACOB QUENTIN UMBERGER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,448,552 Schultze Sept. '7, 1948 2,487,829 Richards Nov. 15, 1949 OTHER REFERENCES 

1. A PHOTOGRAPHIC STRIPPING FILM COMPRISING A HYDROPHOBIC FLEXIBLE SUPPORT, A HYDROPHILIC COLLOID SILVER HALIDE EMULSION LAYER ON THE SUPPORT, A LAYER COMPOSED ESSENTIALLY OF WATER-SOLUBLE QUATERNARY SALT OF A VINYLPYRIDINE POLYMER ON SAID EMULSION LAYER AND A LIGHT-SENSITIVE COLLOID SILVER HALIDE EMULSION LAYER ON SAID POLYMER LAYER.
 17. A PROCESS FOR DECREASING THE WATER-SOLUBILITY OF A STRIPPING LAYER OF A PHOTOGRAPHIC ELEMENT, SAID STRIPPING LAYER SUPPORTING A HYDROPHILIC COLLOID SILVER HALIDE EMULSION LAYER AND CONSISTING ESSENTIALLY OF A WATER-SOLUBLE QUATERNARY SALT OF A VINYLPYRIDINE POLYMER, WHICH COMPRISES TREATING SAID SALT WITH AN AQUEOUS SOLUTION CONTAINING AN ANIONIC WETTING AGENT WHEREIN THE HYDROPHOBIC GROUP IS AN ALIPHATIC HYDROCARBON RADICAL OF 10 TO 18 CARBON ATOMS. 